.login{
    width: 300px;
    height: 300px;
    background: white;
    border: 1px solid;
    position: absolute;
    left: 0;
    top: 40px;
    z-index: 2;
}
.title{
    height: 30px;
    background: gray;
    color: white;
}
.title .close{
    float: right;
}
#mark{
    width: 500px;
    height: 500px;
    background: black;
    opacity: 0.5;
    position: absolute;
    left: 0;
    top: 0;
    z-index: 1;
}